Aaron Bernstein/Reuters

“I agreed to receive a copy of what is now referred to as ‘the dossier,’” McCain writes in the upcoming book, titled The Restless Wave, referencing information compiled by former British intelligence officer Christopher Steele. “I reviewed its contents. The allegations were disturbing, but I had no idea which if any were true. I could not independently verify any of it, and so I did what any American who cares about our nation’s security should have done.”

The Daily Beast obtained an advance copy of the book, due out May 22.

McCain writes that in November 2016, he spoke with Sir Andrew Wood, a former British diplomat, at the Halifax International Security Forum. Wood alerted him to Steele’s work after which, David Kramer, senior director for Human Rights and Human Freedoms at the McCain Institute, traveled to London to meet with Steele. Prior to this, as The Washington Postreported, Steele had already met with American officials in Rome to discuss his findings. The Arizona Republican had previously issued a statement in January of 2017 about passing over "sensitive information" to Comey.

McCain recounts how he put the dossier in a safe in his office and called Comey’s office to request a meeting: “I went to see him at his earliest convenience, handed him the dossier, explained how it had come into my possession.

“I said I didn’t know what to make of it, and I trusted the FBI would examine it carefully and investigate its claims. With that, I thanked the director and left. The entire meeting had probably not lasted longer than ten minutes. I did what duty demanded I do,” McCain concludes.

“He has declined to distinguish the actions of our government from the crimes of despotic ones,” McCain writes. “The appearance of toughness, or a reality show facsimile of toughness, seems to matter more than any of our values.”